The present disclosure relates generally to multicast and unicast forwarding in a computer network.
In multicast data transmission, data packets originating from a source node are delivered to a group of receiver nodes through a tree structure. Unicast communications take place between a single sender and a single receiver.
Certain applications such as Virtual Private Local Area Network (LAN) Services (VPLS) require a combination of unicast forwarding to one of many receivers and multicast forwarding to all of the receivers. This is implemented in conventional systems through the use of unicast labels exchanged by Label Distribution Protocol (LDP) and the replication of frames at the sender to broadcast messages. This is, however, expensive from a data perspective.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.